An acetabular implant essentially comprises a metallic cup with a generally hemispherical shape that will be impacted in the acetabular cavity of the iliac bone, in different arrangements, in combination or not in combination with cement. In general, the cup receives a polyethylene, ceramic or metal kernel that will cooperate with a femoral head of a complementary femoral implant, while maintaining an articulation capability. The kernel may be implanted in the internal cavity of the cup, either in a fixed manner or with a displacement or multidirectional capability.
Obviously, different arrangements will have to be made depending on the nature of the kernel (mobile or fixed with respect to the metallic cup). In other words, it is impossible to use the same metallic cup for the assembly of a mobile kernel and for the assembly of a fixed kernel.
For example, consider the information given in patent FR 2 795 302 that describes an acetabular implant comprising a cup that can hold a fixed insert or a mobile insert fixed onto a mobile kernel, while a mobile insert holds a fixed kernel. The solution described in this patent enables only the assembly of a kernel with freedom to move or the assembly of a kernel fixed to an insert mounted with freedom to move in the hemispherical cavity of the cup. The result is that the kernel cooperating with this femoral head is always free to move with respect to the cup.